Background: Apneic oxygenation (ApOx) is the passive flow of oxygen into the alveoli during apnea. This passive movement occurs due to the differential rate between alveolar oxygen absorption and carbon dioxide excretion producing a mass flow of gas from the upper respiratory tract into the lungs. Another important component of this maneuver is maintaining a patent airway so that supplemental oxygen administered through the nares is able to be delivered to the alveoli. This practice has been a game changer in emergency airway management for many providers. However, there are still some naysayers that believe in the sickest patients ApOx may not be so beneficial. This post is a review of two recent systematic reviews/meta-analyses published in the critical care and ED/retrieval settings on the use of ApOx.

Review #1: Pavlov I et al [1]:

What They Did:

Systematic review and meta-analysis of studies using apneic oxygenation performed in critical care settings

Studies that did not have control groups (Authors included observational studies to increase the power of their review. Observational studies don’t really have control groups .They have exposed and non-exposed groups.)

First systematic review and meta-analysis to investigate use of apneic oxygenation during intubation in the ED and retrieval settings

Limitations:

There was only one high quality RCT; All other studies included were low quality evidence (i.e. 3 low quality prospective comparative trials, 1 retrospective comparative trial and 1 retrospective observational trial)

Significant heterogeneity between studies

Study protocols differed in their methods of pre-oxygenation (i.e. some used positive pressure ventilation)

Lack of all-cause 30 day mortality analysis

Discussion:

In the second study, relative risk reduction was used, however many of us prefer absolute risk reduction. We went ahead and calculated this:

Desaturation: ARR 5.9% with a NNT = 16.8 to avoid one desaturation event

Clinical Take Home Point: Use of Apneic Oxygenation (ApOx) in adult patients requiring emergency intubation, without shunt physiology, in critical care settings, the ED, and retrieval settings is a low cost, low complexity maneuver, and reduces the incidence of hypoxemia and increases first pass intubation rates based on limited studies. Further prospective, randomized trials would be ideal but, in the absence of better evidence, this intervention should be part of everyday clinical practice during emergency intubation, unless future high quality randomized controlled trials prove otherwise.